Aerosol cap and method for its production



July 18, 1967 H. HAFNER ETAL 3,331,422

AEROSOL CAP AND METHOD FOR ITS PRODUCTION Filed Feb. 11, 1965 2 Sheets-Sheet 1 4 J "I I" I2 19 m I /9 A I HHI' n ,4 /2

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AEROSOL CA1 AND METHOD FOR ITS PRODUCTION Filed Feb. 11, 3.965 2 Sheets-Sheet 2 INVENTORS CHRIST/AN BAYER HANS HAFNER United States Patent 3,331,422 AEROSOL CAP AND METHOD FOR ITS PRODUCTION Hans Hafner, Yonkers and Christian Bayer, Armonk, N.Y., assignors to Polymer Products Corporation, Yonkers, N.Y., a corporation of New York Filed Feb. 11, 1965, Ser. No. 431,813 6 Claims. (Cl. 150-52) This invention relates to a removable, protective cover for the dispensing head of a packaging unit and particularly a cover for an aerosol container and to the method for its production. While the invention will be described hereafter in relation to a cover for an aerosol dispensing cap, it should be understood that the invention is equally useful as a protective cover for other objects; those skilled in the art having the benefit of this disclosure seeing the utility of the cover for other than an aerosol cap.

Problems attending the storage of aerosol containers include the accidental or intentional discharge when handled. Moreover, the plastic caps used for such containers collect dirt. This problem is accentuated by the fact that such plastics may carry or develop static charges which will attract dust particles.

We have found that these problems may be eliminated by rendering the cap relatively tamper-proof and dirtproof by covering the cap with a thin plastic film which is removable prior to the first use of the aerosol container, yet retaining the aesthetic effect created by the peripheral contour of the under cap.

Broadly, the cover of this invention comprises a relatively thin plastic film drawn over the aerosol cap to provide a taut skin therefor, said skin being adhered, preferably heat sealed, at its terminal edge to the cap.

In the figures:

FIG. 1 depicts one form of an aerosol cap having a top located actuator which cap 10 fits on an aerosol container and releases its contents when the actuator is depressed.

FIG. 2 shows such a cap 11 covered with a plastic film 12 in accordance with the present invention.

FIGS. 3-6 depict apparatus for carrying out the method of this invention; and

FIGS. 7 and 8 show the inverted cap '10 with a lower edge 22 and the overlaying film 12 heat-sealed, alternativedly, on the side of the cap at 23 or on its upper edge at 24.

In carrying out this invention, it has been found that polyethylene of varying density grades may be used. For example, polyethylene of a density range .93.97 is suitable. The preferred film material is biaXially-oriented plastic film compounded from about 70% high density polyethylene and 30% polyisobutylene having a molecular weight of about 80,000 to 120,000. Also a plastic film comprising polyethylene in the range of 40 to 85% and the balance polyisobutylene having a molecular weight in the range of 30,000 to 350,000 are suitable. Other thermoplastic films may be used provided they can be stretched at about room temperature, retain the stretch for a short period, and have adequate tear resistance. For example, polypropylene, ethylene vinyl acetate copolyrner, cellulose acetate, cellulose acetate butyrate. In general, thermoplastic film material having a percentage elongation of 350-1000 is suitable, preferably the range is 600-800.

The film may contain other additives to prevent degradation, such as 3,5-tertiary butyl, 4-hydroxy toluene.

Example In the preferred manner of carrying out our invention 3,33l/i-22 Patented July 18, 1967 about 70% high density polyethylene and about 30% polyisobutylene having a molecular weight of 100,000 are compounded in a Banbury mixer. A small amount of a compound, such as 3,5-tertiary butyl, 4-hydroxy toluene, is added to prevent premature degradation. This blend of polymers is then extruded in tube form by a conventional method and known as lay flat or blown film, and rolled up. During the laying out and rolling up of the tube, the polymer film is stretched and is biaxially oriented, giving it added strength and rendering it more suitable for use in carrying out our invention. It is prefererd to use a polymeric sheet or film which has been biaxially oriented to some degree but a film which has not been so treated may still be used in carrying out the invention. Such a polymer may also be biaxially oriented by other known methods.

A single layer of the polyethylene-polyisobutylene sheeting of a thickness of about 1 to 7 mils is laid across the apparatus of FIG. 3. The apparatus comprises a cylindrical male die 13 and a cavity containing member 14. Movable in such cavity is a top closed cylinder member 15 having a base shoulder portion 16 and attached springs 17. Support means 18 are provided for the spring. Not shown are means for supporting the male die 13, the

' member 14 and the spring base member 18. The apparatus shown in FIGS. 3 to 6 may be constructed of metal or other suitable hard material.

In forming the cover, the film 12 is disposed across the top surface of the member 14 and clamped at 19. The relation of the male die 13, film 12 and the cylinder 15 just prior to actuation of the male die 13 is as shown in FIG. 3. As shown in FIG. 4, the male die 13 is advanced downwardly stretching the film and clamping it between itself and the topsurface of the cylindrical member 15. The male die 13 is then further advanced as shown in FIG. 5 thereby further stretching the side walls of the film 12 but not to any substantial degree the portion of film 12 engaged between the die 13 and the cylinder member 15.

After the film has been stretched as shown in FIG. 5, the male die 13 is removed, the cylinder member 15 by spring action, retracts from the cavity until the base portion 16 is in contact with the lower shoulder of the member 14. The clamps 19 are released, and the apparatus is ready for a repeat of the operation. Means for lowering and raising the die 13 are not shown. The stretching of the film is carried out at about room temperature. Thereafter the film, substantially in its stretched condition, is transferred to a clamping member 20 and held by clamps 21.

The diameter of the cylindrically indented part of the film 12 as shown in FIG. 6 is slightly less than that of the inverted aerosol cap 10 as shown in FIG. 6. The cap is then lowered and the film stretched over it, usually to an extent that the film is drawn beyond the edge 22 of the cap. The film, by means not shown, is then folded over the edge 22 of the cap. This may be done by a cold knife projecting at an angle down inside the cap and the film is then heat-sealed at or near the end of the cap 24, FIG. 8, by use of a hot knife or disc (not shown). It may also be heat-sealed near the end of the cap 10, FIG. 7, by placing a dielectric ring around the film at 23, FIG. 7, and heating the ring to heat-seal the film on the cap.

The procedure described above, involving a two stage stretch operation, is particularly adaptable to aerosol caps in which the advancing end of the cap has relatively sharp edges. In the instance where the cap has relatively rounded edges,'the stretch operation may be performed in a single stage by substituting the cap 10 for the male die 13, as shown in FIGS. 3-5 and advancing same to the desired extent into the polymeric film.

- a A further feature of this invention is that advancing the top portion of the cap into the thin polymeric film results in a moderate stretching of the film covering the top portion relative to the stretching of the film covering the side wall and consequently a difference in thickness between said top portion and the side wall. This difference in thickness provides a line of Weakness and facilitates the rupture of the film. Moreover, the thicker top portion is of advantage in rendering the cap tamperproof. Finally it is desirable to have the top portion thicker so that printing thereon will not be distorted.

As shown by FIG. 2, the cap has been rendered tamperproof; the film is substantially flat across the top of the cap and above the actuator of the aerosol container. The container may then be discharged only by breaking or distending the film covering the cap. If the film is broken it will show the tampering, and if the film is distended to release any contents of the aerosol container, the film will shown the discharge. The film will also serve to keep the cap dirt-free until the film is removed by the user prior to the first use of the aerosol container.

We claim: 1

1. A tamper-proof aerosol cap comprising a caphaving a depressed actuator in the top opening thereof and further having a thin polymeric film drawn tightly over 4. The cap of claim 1,'wherein the polymer is 40 to' 85% polyethylene and the remainder is. substantially polyisobutylene.

5. The product of claim 1, wherein the polymer is a blend of about high density polyethylene and about 30% polyisobutylene.

6. The cap of claim 2, wherein the polymer has been biaxially oriented.

References Cited UNITED STATES PATENTS 1,520,940 12/1924 Dulitz 21538 3,022,543 2/1962 Baird et al. l857 3,198,399 8/1965 Sagarin 222l82 FRANKLIN T. GARRETT, Primary Examiner. 

1. A TAMPER-PROOF AEROSOL CAP COMPRISING A CAP HAVING A DEPRESSED ACTUATOR IN THE TOP OPENING THEREOF AND FURTHER HAVING A THIN POLYMERIC FILM DRAWN TIGHTLY OVER THE SIDE AND TOP PORTIONS OF SAID CAP, AND WHEREIN THE FILM ACROSS THE TOP PORTION IS ELEVATED ABOVE THE ACTUATOR AND IS SUBSTANTIALLY FLAT. 